There is a need to clean lubricated vapor compression systems and their components during manufacture and service.
Vapor compression air conditioning and refrigeration systems are well known in the art. They are used in a wide variety of applications such as heating, air conditioning, and refrigeration. By compressing and expanding a heat transfer agent or refrigerant, these systems absorb and release heat according to the needs of a particular application. Common components of a vapor compression system include: vapor or gas compressors; liquid pumps; heat-transfer equipment such as gas coolers, intercoolers, aftercoolers, heat exchangers, economizers; vapor compressors, such as reciprocating piston compressors, rotating screw compressors, centrifugal compressors, and scroll compressors; evaporators; liquid coolers and receivers; expanders; control valves and pressure-drop throttling devices such as capillaries and orifice tubes; refrigerant-mixture separating chambers; and connecting piping and insulation. These components are typically fabricated from aluminum, copper, brass, steel, various plastics and conventional gasket and O-ring materials.
Since vapor compression systems have sliding, rotating or other moving components, most require the use of a lubricant which is mixed with the refrigerant. There is a need from time to time to clean such systems and their components by removing the lubricants as well as other contaminants and debris from their surfaces. Such a need arises, for example, during the retrofit of a chlorofluorocarbon (CFC) to a hydrochlorofluorocarbon (HCFC) or hydrofluorocarbon (HFC), or retrofit of a HCFC refrigerant to a HFC refrigerant, and during service, especially after a catastrophic event such as compressor burnout or mechanical failure.
Until recently, CFCs, such as trichloromethane (R-11), and HCFCs, such as 1,1-dichloro-1-fluoroethane (HCFC-141 b), were used as cleaning agents for such systems. Although effective, CFCs and HCFCs are now considered environmentally unacceptable because they are believed to contribute to the depletion of the stratospheric ozone layer. As the use of CFCs and HCFCs is reduced and ultimately phased out, new cleaning agents are needed that not only perform well, but also pose no danger to the ozone layer.
A number of environmentally acceptable solvents have been proposed, but their use has been met with limited success. For example, organic solvents, such as hexane, have good cleaning properties and do not deplete the ozone layer, but they are flammable. Aqueous-based cleaning compositions have zero ozone depletion potential and are non-flammable, but they tend to be difficult to remove from the cleaned surfaces due to their relatively low volatility and the presence therein of additives that leave a residue. Additionally, aqueous-based cleaning compositions are often inadequate for cleaning typical organic soils that are present in vapor compression systems. Terpene-based solvents, like aqueous-based cleaning compositions, are difficult to remove from the system.
Therefore, a need exists for the identification of environmentally-acceptable cleaning agents that effectively clean vapor compression systems. The present invention fulfills this need.